[RESEND 1/3] venus: core: handle race condititon for core ops

From: Mansur Alisha Shaik
Date: Fri Aug 07 2020 - 02:25:21 EST

For core ops we are having only write protect but there
is no read protect, because of this in multthreading
and concurrency, one CPU core is reading without wait
which is causing the NULL pointer dereferece crash.

one such scenario is as show below, where in one
core core->ops becoming NULL and in another core
calling core->ops->session_init().

CPU: core-7:
Call trace:
hfi_session_init+0x180/0x1dc [venus_core]
vdec_queue_setup+0x9c/0x364 [venus_dec]
vb2_core_reqbufs+0x1e4/0x368 [videobuf2_common]
vb2_reqbufs+0x4c/0x64 [videobuf2_v4l2]
v4l2_m2m_reqbufs+0x50/0x84 [v4l2_mem2mem]
v4l2_m2m_ioctl_reqbufs+0x2c/0x38 [v4l2_mem2mem]

CPU: core-0:
Call trace:
venus_shutdown+0x98/0xfc [venus_core]
venus_sys_error_handler+0x64/0x148 [venus_core]

Signed-off-by: Mansur Alisha Shaik <mansur@xxxxxxxxxxxxxx>
drivers/media/platform/qcom/venus/core.c | 2 +-
drivers/media/platform/qcom/venus/hfi.c | 5 ++++-
2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/media/platform/qcom/venus/core.c b/drivers/media/platform/qcom/venus/core.c
index 203c653..fe99c83 100644
--- a/drivers/media/platform/qcom/venus/core.c
+++ b/drivers/media/platform/qcom/venus/core.c
@@ -64,8 +64,8 @@ static void venus_sys_error_handler(struct work_struct *work)

hfi_core_deinit(core, true);
- hfi_destroy(core);
+ hfi_destroy(core);

diff --git a/drivers/media/platform/qcom/venus/hfi.c b/drivers/media/platform/qcom/venus/hfi.c
index a211eb9..2eeb31f 100644
--- a/drivers/media/platform/qcom/venus/hfi.c
+++ b/drivers/media/platform/qcom/venus/hfi.c
@@ -195,7 +195,7 @@ EXPORT_SYMBOL_GPL(hfi_session_create);
int hfi_session_init(struct venus_inst *inst, u32 pixfmt)
struct venus_core *core = inst->core;
- const struct hfi_ops *ops = core->ops;
+ const struct hfi_ops *ops;
int ret;

if (inst->state != INST_UNINIT)
@@ -204,10 +204,13 @@ int hfi_session_init(struct venus_inst *inst, u32 pixfmt)
inst->hfi_codec = to_codec_type(pixfmt);

+ mutex_lock(&core->lock);
+ ops = core->ops;
ret = ops->session_init(inst, inst->session_type, inst->hfi_codec);
if (ret)
return ret;

+ mutex_unlock(&core->lock);
ret = wait_session_msg(inst);
if (ret)
return ret;
QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member
of Code Aurora Forum, hosted by The Linux Foundation